I HAVE TO PAY TAXES ON THE COST BASIS OF MY 401K STOCK DISTRIBUTION. I AM SINGLE. THE COST BASIS IS $345,791.35. CAN ANYONE TELL ME THE MARGINAL BRACKET AND TAX

MY NON ESOP PLAN IS BEING CLOSED.  IT IS A 401K.  I HAVE A COST BASIS FOR STOCK DISTRIBUTION OF $345,791.00.  I AM NOT SURE OF MY MY MARGINAL TAX BRACKET.  WHAT IS MY TAX APPROXIMATELY WITH ONLY A STANDARD DEDUCTION.